Sufficient Conditions for First-Order and Datalog Rewritability in ELU.
Mark Kaminski, Bernardo Cuenca Grau · 2013
Abstract. We study the problem of answering instance queries over non-Horn ontologies by rewriting them into Datalog programs or First-Order queries (FOQs). We consider the basic non-Horn language ELU, which extends EL with disjunctions. Both Datalog-rewritability and FOrewritability of instance queries have been recently shown to be decidable for ALC ontologies (and hence also for ELU); however, existing decision methods are mainly of theoretical interest. We identify two fragments of ELU for which we can compute Datalog-rewritings and FO-rewritings of instance queries, respectively, by means of a resolution-based algorithm. 1